Voltage regulator



y 1956 A. BUNBLASKY ETAL 2,744,231

VOLTAGE REGULATOR Filed June 14, 1952 IN VEN TORS. ADOLPH BUNBLASKY ALLEN K. BROWN BY Dike/L.

ATTORNEY United States Patent VOLTAGE REGULATOR Adolph Bunblasky, Ridgefield, and Allen K. Brown, Stamford, Conn., assignors to Sorensen & Company, Incorporated, Stamford, Conn.

Application June 14, 1952, Serial No. 293,531 3 Claims. (Cl. 323-66) This invention relates to voltage regulators and has particular reference to circuit means for attaining more accurate regulation than has been possible with prior art circuits.

Prior art circuits for regulating an output circuit of an alternating current supply have succeeded in regulating the voltage within a range of somewhat less than 1 per cent when the supply voltage varies Within a range of per cent. While such a regulation is satisfactory for most engineering applications it is often desirable to produce an output voltage which varies less than one tenth of one per cent under the same supply conditions. The present invention provides such a circuit using many of the prior art circuit arrangements but in addition using a positive sensing circuit which makes the regulator system more accurate and quicker in response.

One of the objects of this invention is to provide an improved regulator circuit which avoids one or more of the disadvantages and limitations of prior art arrangements.

Another object of the invention is to increase the accuracy of voltage regulator systems.

Another object of the invention is to improve the quality of voltage regulator systems without increasing the cost.

One feature of the invention comprises a filamentary diode having its filament connected to the output terminals of a voltage regulator circuit. The filament is also connected to a direct current supply circuit which derives its power from the input circuit. The variation of im pedance of the filamentary diode is utilized to provide a control current through a saturable reactor, the variable reactance portion of this circuit being connected to the input circuit so that a variation of reactance produces a variation of output voltage.

For a better understanding of the present invention, together with other and further objects thereof, reference is made to the following description taken in connection With the accompanying drawing.

The figure is a schematic diagram of connections of a voltage regulator.

The voltage regulator system shown in the drawing is connected to an alternating current supply line by means of terminals 10, 11. Bridged across these terminals is an autotransformer 12 and the alternating current winding 13 of a saturable reactor. Connected across terminal 11 and one end of the autotransformer is a power transformer 14 which in this case is used to step down the alternating current voltage to a load circuit which contains rectifiers 15, 16 and a six volt line for supplying direct current to an external load 18. It will be ob vious that other types of rectifying circuits may be used in place of rectifiers 15, 16 and also from the description which follows it will be obvious that the circuit will work equally Well with an alternating current output. Connected across output terminals 17 is a voltage divider 20, 21 by means of which other direct current voltages may be obtained.

The circuit also contains power transformers 22 and 23 used for producing direct current sources for the operation of an amplifier system which transmits the variations of impedance of a filamentary diode into a direct current for controlling the input voltage. Transformer 22 comprises a primary winding 24 and a secondary winding 25 for supplying the anodes of a double diode rectifier tube 26. Another secondary winding 27 supplies the filament or heater current for tube 26. Supplementing this rectifier circuit is a choke coil 28 and a capacitor 30. This arrangement supplies a voltage of about 300 volts between conductors 31 and 32.

A second rectifier system includes a secondary winding 33 on transformer 22 and a rectifier unit 34 in series with one of the conductors from winding 33. This rectifier provides a direct current voltage of about 200 volts between conductors 35 and 32.

A third rectifier system includes a 36 on transformer 23 which is employed to supply the anodes of a double rectifier tube 37. Another secondary winding 38 supplies the filament or heater current for the rectifier tube. This rectifier system provides a voltage of about 150 volts between conductors 40 and 41.

In order to stabilize the direct current voltages produced by these rectifier systems a series of voltage regulator tubes are placed across the output circuit. These voltage regulator tubes are the Well known gas filled types and absorb voltage variations due to the characteristics of their gaseous discharge. Voltage regulator tubes 42 are placed across the output of the second rectifier and also are a means for dividing the voltage to produce an intermediate voltage on conductor 43. Voltage regulator tubes 44 are bridged across part of the supply line which furnishes the voltage for the anode of a filamentary diode 45. Voltage regulator tubes 46 are employed to stabilize the output of the third rectifier while voltage regulator tubes 4'7 are employed to stabilize the voltage of a control electrode in an amplifier tube.

Diode has its filament connected across the output terminals 17 of the regulator system. A variable resistor 50 is employed to reduce the filament current to a desired value when the output voltage is properly regulated. Variations in the voltage applied to the filament of diode 45 cause variations in impedance between the filament and the anode of tube 45. These variations are applied to anode conductor 51 which is connected to the control electrode of an amplifier tube 52. This tube is connected by a cathode follower coupling to a second amplifier tube 53 and variations of voltage on the control electrode of amplifier tube 52 produce variations in current through cathode resistor 54 and thereby vary the voltage of the cathode of tube 53. Since the control electrode of tube 53 is stabilized at a constant voltage, the variation of cathode potential produces a variable anode current which is applied to conductor 40 and transmitted as a reduced voltage value over conductor 41. Conductor 41 is connected through a filter circuit 55 to the control electrode of a third amplifier tube 56. The anode current of this amplifier tube passes through a direct current Winding 57 of the saturable reactor thereby controlling the amount of reactance bridged across the input terminals 10, 11.

In order to supply a more positive sensing arrangement between a portion of the input circuit and the regulating system, a connection is made between conductor 31 and the positive lead which connects to the filament of diode 45. This connection includes conductor 58 in series with a resistor 60, the value of resistor 60 determining the sensitivity of this circuit. A second coupling arrangement which increases the sensitivity of the circuit includes a conductor 61 which connects the cathode of tube 56 with the filament of diode 45. The sensitivity of this circuit depends upon the value of resistor 62.

secondary winding The operation of this circuit is as follows: Under normal conditions when the alternating current supply is not variable the output voltage at terminal 17 is the desired value which applies an intermediate potential to the filament of diode 45 causing it to assume a desired temperature and to produce an average value of anode cathode impedance. These conditions produce intermediate values of operating potentials for the three amplifier tubes 52, 53, and 56 causing a current to flow through winding 57 and control the reactance of winding 33 to stabilize it at an average desired value. feed back connection through resistor 60 and conductor 53 supplies a small amount of the direct current used by the filament of'diode 45.

Now let it be assumed that the input voltage applied to terminals 10, 11 is increased. This tends to cause a similar increase in voltage across the output terminals l7 and this voltage applied to the filament of diode 45 increases the temperature of the filament and lowers the impedance between the anode and cathode. tion to the increase in current supplied by output terminals 17, the current to the filament of diode do" is also increased by an increase of the direct current through circuit d0, 53. This second increase in current is derived from the rectifier system supplied by transformer 22 and represents a more positive increase than the variation due to the voltage change on the output terminals.

A third increase in the filament current of diode 4-5 is due to conductor 61 which carries the cathode current of amplifier tube 56. This current passes through resister 62 and thereby controls the potential across the filament terminals An increase in voltage on the A. C. line increases the potentials in rectifier 22 and the voltage applied to the anode of amplifier tube 56 The result is an increase in direct current through the tube and through conductor 61.

When the impedance of diode 45 is decreased, the current through the tube increases and the potential of conductor 51 is lowered, thereby reducing the potential on the control electrode of amplifier tube 52 and lowering the current through cathode resistor 54. This action results in a reduction of the voltage on the cathode of amplifier tube 53 and an increase in the anode-cathode current through the tube. This in turn reduces the potential on conductors 40 and 41 and applies a reduced voltage to the control electrode of amplifier tube 56 thereby reducing the anode-cathode current through that tube and reducing the current through winding 5'7 of the saturable reactor. This increases the reactance and impedance of winding 13 and produces a reduced voltage applied to transformer 14 and the output terminal.

The action described above is continuous and occurs whenever the load voltage is greater or less than the desired voltage. Whenever the load voltage is equivalent to the desired voltage there is no amplifier action and no change in the direct current in the direct current winding of the saturable core reactor.

The following circuit constants may be used in the circuit shown in the figure, and are illustrative of a specific application of the invention.

Tube 56 Type 6L6. Tubes 52 and 53- Type 65N7. Diodes 42 Type VR75.

Diodes 46 Type VR105.

Under these conditions the in addi- Diodes 44 and 47 Type NE-16. Resistance 60 330,000 ohms. Resistance 62 2 ohms. Resistance 54 15,000 ohms.

While there have been described and illustrated specific embodiments of the invention, it will be obvious that various changes and modifications may be made therein without departing from the field of the invention which should be limited only by the scope of the appended claims.

I claim:

1. A voltage regulator circuit for supplying a constant voltage to a load comprising, input terminals for connection with an alternating current supply, a saturable reactor connected across the input terminals in series with an autctransfonner, said saturable reactor controlled by a dire-ct current applied to one winding thereof, a variable impedance diode containing a filamentary cathode which is connected across .the load, an amplifying circuit connectcd between the diode and the direct current winding on the saturable reactor, and a circuit coupled to the input terminals which sends current through the filamentary cathode, the magnitude of said current varying in proportionto the input voltage.

2. A voltage regulator circuit for supplying a constant voltage to a load comprising, input terminals for connection with an alternating current supply, a saturable reactor connected across the input terminals in series with an auto-transformer, said saturable reactor controlled by a direct current applied to one winding thereof, a coupling circuit connected between the autotransformer and the load, a variable impedance diode containing a filamentary cathode which is connected across the load, an amplifying circuit connected between the diode and the direct current winding on the saturable reactor, and acircuit coupled to the input terminals which sends current through the filamentary cathode, the magnitude of said current varying in proportion to the input voltage.

3. A voltage regulator circuit for supplying a constant voltage to a load comprising, input terminals for connection with an alternating current supply, a saturable reactor connected across the input terminals in series with an autotransformer, the reactance of said saturable reactor controlled by a direct current applied to one winding thereof, a coupling circuit connected between the autotransforrner and terminals of the load, a variable impedance diode having a direct current anode supply and arranged for sensing the voltage variations applied to the load, said diode containing a filamentary cathode which is connected across the load terminals in series with a manually adjustable resistor, an amplifying circuit cornprising amplifying tubes and coupling circuits connected between the diode and the direct current winding in the saturable reactor, and a circuit coupled to the input terminals which sends current through the filamentary cathode, the magnitude of said current varying in proportion to the input voltage.

References Cited in the file of this patent UNITED STATES PATENTS 2,569,500 Sorenson Oct. 2, 1951 

